Charging a battery pack from a solar panel?

A  part of my culminating project to graduate from my technical school involves a simple circuit. I want to have a solar panel charge a 7.2v battery pack. This will then output to a female USB port for charging mobile devices. I have majority of my circuit figured out. However, I am not sure how I can effectively regulate the charging of the battery. I know I need a solar panel that outputs higher voltage than the battery, and a Diode in between to prevent backflow into the panels. However, How would I prevent overcharging?

Use a charge control IC. For further credit, use a MPPT IC.

Stephen Woodward did a rather clever discrete circuit years ago in Electronic Design IIRC.

If this is for a final project, it would be unfair to give you much more information.
dkop1 (author)  steveastrouk4 years ago
True, it would be rather Unfair. Thank you for the info!
Do some more research, and by all means, we'll critique it and help - but start with the research.....

With the right charger topology, your panel can be lower voltage than your battery.....